Broken metadata error propagation

strax/storage/files.py

@@ -208,6 +208,14 @@ class FileSytemBackend(strax.StorageBackend):
     """
 
     def get_metadata(self, dirname):
+        try:
+            return self._get_metadata(dirname)
+        except strax.DataCorrupted:
+            raise
+        except Exception as e:
+            raise strax.DataCorrupted(f'Cannot open metadata in {dirname} from {e}')
+
+    def _get_metadata(self, dirname):
         prefix = dirname_to_prefix(dirname)
         metadata_json = f'{prefix}-metadata.json'
         md_path = osp.join(dirname, metadata_json)

tests/test_saving.py

@@ -1,6 +1,6 @@
 import unittest
 import strax
-from strax.testutils import Records
+from strax.testutils import Records, Peaks
 import os
 import shutil
 import tempfile
@@ -12,7 +12,8 @@ def setUp(self):
         self.test_run_id = '0'
         self.target = 'records'
         self.path = os.path.join(tempfile.gettempdir(), 'strax_data')
-        self.st = strax.Context(register=[Records],
+        self.st = strax.Context(use_per_run_defaults=True,
+                                register=[Records],
                                 storage=[strax.DataDirectory(self.path)])
         assert not self.st.is_stored(self.test_run_id, self.target)
 
@@ -58,3 +59,39 @@ def set_save_when(self, mode: str):
             raise ValueError(f'No such saving mode {mode}')
         save_mode = getattr(strax.SaveWhen, mode.upper())
         self.st._plugin_class_registry[self.target].save_when = save_mode
+
+    def test_raise_corruption(self):
+        self.set_save_when('ALWAYS')
+        self.st.make(self.test_run_id, self.target)
+        assert self.is_stored()
+        storage = self.st.storage[0]
+        data_key = self.st.key_for(self.test_run_id, self.target)
+        data_path = os.path.join(storage.path, str(data_key))
+        assert os.path.exists(data_path)
+        metadata = storage.backends[0].get_metadata(data_path)
+        assert isinstance(metadata, dict)
+
+        # copied from FileSytemBackend (maybe abstractify the method separately?)
+        prefix = strax.dirname_to_prefix(data_path)
+        metadata_json = f'{prefix}-metadata.json'
+        md_path = os.path.join(data_path, metadata_json)
+        assert os.path.exists(md_path)
+
+        # Corrupt the metadata (making it non-JSON parsable)
+        md_file = open(md_path, 'a')
+        # Append 'hello' at the end of file
+        md_file.write('Adding a non-JSON line to the file to corrupt the metadata')
+        # Close the file
+        md_file.close()
+
+        # Now we should get an error since the metadata data is corrupted
+        with self.assertRaises(strax.DataCorrupted):
+            self.st.get_array(self.test_run_id, self.target)
+
+        # Also test the error is raised if be build a target that depends on corrupted data
+        self.st.register(Peaks)
+        with self.assertRaises(strax.DataCorrupted):
+            self.st.get_array(self.test_run_id, 'peaks')
+
+        # Cleanup if someone wants to re-use this self.st
+        del self.st._plugin_class_registry['peaks']